SURG-33. Spinal myxopapillary ependymomas: the role of surgery and radiation therapy

Abstract BACKGROUND Myxopapillary ependymomas (MPE) are slow-growing spinal tumors typically arising in the cauda equina but classified as WHO grade 2 due to local aggressiveness and recurrence. Given their rarity, the impact of radiation and resection technique (piecemeal vs. en bloc) on recurrence and survival remains unclear. METHODS We retrospectively reviewed patients who underwent surgery for MPE between 2000 and 2024, excluding other spinal ependymal tumor subtypes. Progression-free survival (PFS) was analyzed using Kaplan–Meier curves and log-rank tests across sex, EOR, RT, cysts, and resection technique (en bloc vs. non–en bloc). A multivariable Cox model with Firth’s correction identified independent predictors of recurrence. Proportional-hazards assumptions were verified using Schoenfeld residuals. All analyses were two-sided (α = 0.05) and conducted in RStudio. RESULTS We included 63 patients (median age: 37 years; 44.4% female; BMI: 26.5 kg/m²). Preoperative KPS was 90, and Frankel E–D status was recorded in 95% of cases. Three patients had intracranial dissemination. The most affected level was lumbar (51%), followed by sacral (32%). Imaging showed heterogeneous enhancement in 52.4% and no enhancement in 10%; cysts were absent in 81%. GTR was achieved in 83% (piecemeal: 60%, en bloc: 40%). Seventeen patients experienced intraoperative neuromonitoring changes, all returning to baseline. Early postoperative Frankel E–D was seen in 92.4%. At two years, median KPS was 95. Mean PFS was 63 months. Kaplan–Meier analysis showed worse PFS in sacral tumors. En bloc resection and piecemeal resection with radiation had better PFS than piecemeal alone. Multivariate analysis identified GTR, proton therapy, and lumbar location as independent predictors of improved PFS. CONCLUSION Complete resection (i.e., GTR), particularly en-bloc, and proton therapy were associated with improved progression-free survival in MPEs. These findings support a tailored approach to maximize resection and consider adjuvant therapy selectively, especially in piecemeal cases or those with unfavorable anatomical location